The spine is formed with 24 vertebrae overlapping one over the other in the vertical direction, and the vertebrae are connected by the intervertebral disc. As shown in FIG. 13, the intervertebral disc is a circular disc shaped cartilage having fibrous ring surrounding the nucleus pulposus of jelly form at the center, and has a function of alleviating the impact. The vertebra is made up of the vertebral body and the vertebral arch of the back, and vertebral foramen is formed between the vertebral arches. The spinal cord runs through the vertebral foramen.
Disk herniation occurs at the spine such as the cervical vertebra, lumbar vertebra, etc. and may be a state (exuding type) in which cracks form in the fibrous ring, and nucleus pulposus therein exudes out therefrom, and a state (bulging type) in which cracks do not form in the fibrous ring and nucleus pulposus and the fibrous ring bulge out together, where symptoms such as severe pain, swelling, etc. occur since the spinal cord and the nerve root on the back side are compressed by the exuded (bulged out) nucleus pulposus.
Treatment includes conservative treatment and operation, where operation is performed if not curable with the conservative treatment. The operation includes Love method of extracting the hernia, vertebral body fixing method, intervertebral disc enzyme injection treatment of injecting enzyme into the intervertebral disc through puncture method to reduce the internal pressure and depressurizing the nerve root under compressive stimulation, percutaneous nucleus pulposus extracting method of partially removing the nucleus pulposus similar to intervertebral disc contrast by external approach without using medicine to reduce the internal pressure of the intervertebral disc, etc.
Among them, the medicinal agent must be accurately injected to the affected area when treating with medicinal agent such as in intervertebral disc enzyme injection treatment. Accuracy is also desired when injecting contrast agent. Normally, the needle is punctured using a puncture tool, and medicinal agent, etc. is injected from the opening at the distal end of the needle when injecting medicine or contrast agent.
However, the direction of puncturing the needle is limited to a constant direction diagonally from the back side due to positional relationship of spinal cord and internal organs, bone, etc. in the operation (FIG. 13). Therefore, the medicinal agent, etc. can be injected only in the puncturing direction of the needle (inserting direction of the needle), whereby the medicinal agent is injected to the entire intervertebral disc and the medicinal agent acts on areas other than the affected area. Conventionally, the medicinal agent thus cannot be injected in a direction different from the puncture direction and it is difficult to exclusively act the medicinal agent on the affected area.
Patent document 1 discloses a device to be inserted into the intervertebral disc in order to perform a certain function inside the intervertebral disc, and a method of the same. This device includes a catheter with a lumen, and a guide wire having a distal end and a proximal end configured so as to be positioned inside the lumen of the catheter and to move with respect to the lumen, the guide wire guiding itself towards the selected portion of the intervertebral disc inside the internal portion of the intervertebral disc, and the catheter moving forward with respect to the guide wire so as to follow the path of the guide wire up to the selected portion inside the internal portion of the intervertebral disc.
[Patent document 1] Japanese Laid-Open Patent Publication No. 2003-523258